Currently there is a need for multi-lumen catheters for a variety of therapies where multiple drug injections are required. Unfortunately, current multi-lumen catheters are positioned in place utilizing a procedure which is bloody, complicated and potentially hazardous to both the patient and the practitioner, especially during central venous catheterization.
A problem with current catheter systems is that once they have been inserted they must be completely removed and replaced if one wants to have more (or less) or cleaner lumens. Thus, a messy and uncomfortable procedure may have to be repeated on a patient whose body is already under stress.
Another problem with existing multi-lumen catheters is that all of the method of inserting them cause blood loss that is dangerous to both the patient and the practitioner. The most common method is to utilize a needle to locate and pierce the blood vessel. A guide wire is then inserted through the needle into the blood vessel. The needle is then removed leaving the guide wire in place. The insertion site if often enlarged by sliding a dilator sheath down the guide wire to stretch open the skin and the vessel wall. The multi-lumen catheter is then slid along over the guide wire and through the now enlarged opening formed by the dilator sheath. Once the catheter has reached the proper location the guide wire and the dilator sheath are removed. The dilator sheath must be removed because its size and stiffness are a potential cause of serious injury (perforation, irritation) to the blood vessel.
Another current alternative is to directly expose and partially transect a vein whereby the catheter may be directly inserted into the vein. This can be a very blood procedure and infection can easily set in.
As mentioned above, another problem with current multi-lumen catheters of the nature disclosed above is that if one wishes to change from, for example, a two lumen catheter to a three lumen catheter, or if one wishes to change the size of the lumens, this can only be accomplished by removing the catheter which is in place and replacing it with another catheter utilizing one of the above mentioned bloody and dangerous techniques.
A catheter system marketed by Arrow International, Inc. under the trademark Arrow-Flex allows for the insertion and removal of an inner cannula through a septum and through the lumen of an outer cannula. This system is, however, designed only for a very short term of use (during an operation) and can only be left in place at great risk to the patient. The outer cannula is made from a stiff polymer to aid in the forceful insertion procedure required to stretch the skin and blood vessel. Also, any liquids being flowed through the outer cannula lumen (i.e., through the annular space between the inner and outer cannulae) must be introduced downstream of the septum whereby the space immediately downstream of the septum (and upstream of the introduction of the liquid) is substantially stagnant. Furthermore, the fact that this space is not flushed out means that if the fluid being flowed through the outer cannula lumen is changed, there will be a transition time during which a mixture of the old and new fluids will be present. As some medicaments are not compatible with others such mixing can be undesirable.
Yet further, the multi-lumen catheters of the prior art have generally been fabricated of materials which are relatively stiff in order to allow them to be inserted and which thereafter remain relatively stiff while they are within the patient's body. As a result, these catheters can cause perforation of major veins which can result in death. For this reason these types of catheters are removed as soon as possible and replaced with softer catheters for the ongoing delivery of medicaments.
The present invention is directed to overcoming one or more of the problems as set forth above.